BEST SPEAKER THAT COMES TO LIFE AT LOW LISTENING LEVELS

JBL 4349.

You have a very nice rig.
I’d start with a Schiit EQ. You can use it like a variable loudness control. The top of the line even has remote.

Run a 1/3rd octave tone generator on your system along with a db meter and you'll likely find out "elliot" is correct and our ears are much more sensitive to tones from around 600hz to 3khz and even if your speakers measure flat they'll sound deficient above and below the midrange. The old Yamaha receivers did have adjustable loudness, but if you don't want to mess around with tone controls and decide to find speakers that use the Fletcher munson curve.There's several brands that design their speakers with that curve in mind and they get great reviews. Raidho is an overpriced example, Vienna Acoustics is a more affordable option that should compensate well for low volume listening. 

Omega Speaker Systems Super Alnico Monitor.

+1 for audiologist appointment.  That will at least tell you where your hearing frequency issues are, which may direct you to a completely different solution than you think. Keep spending money if you like, but at your (our) age, that may not be the fix you are seeking.